Metal esters



United States Patent 3,158,573 METAL ESTERS John A. Kearney, Pennsauken, N.J., assignor to E. F. Houghton & Co., Philadelphia, Pin, a corporation of Pennsylvania N0 Drawing. Filed Jan. 11, 1961, Ser. No. 81,955

14 Claims.

This invention relates to novel esters, to compositions containing such esters, and to methods of making and using these esters. More particularly, it relates to novel esters of hydroxy-substituted fatty acid soaps, to methods of making such esters, to lubricating compositions containing such esters, and to methods of thickening lubricating compositions employing such esters.

It has been known that soaps such as the lithium and aluminum soaps of hydroxy-substituted fatty acids like IZ-hydroxystearic acid are useful in lubricants as grease thickeners. However, these products have limited thickening power and are expensive. It has also been observed that such soaps sometimes exhibit a tendency to cause instability of oleaginous lubricating base fluids comprising hydrolyzable synthetic lubricants such as ester fluids.

Derivatives wherein an organic radical is attached to the hydroxy group of hydroxy-substituted fatty acids have been known'in the art hitherto. However, these materials have also been found deficient in various respects, with regard to utility as lubricating grease thickeners.

An object of this invention is to provide novel chemical compounds.

A particular object of this invention is to provide novel chemical compounds particularly adapted for use as grease thickeners.

A further particular object of this invention is to provide novel lubricating grease compositions comprising an oleaginous base fluid thickened to a grease consistency.

Another object is to provide a novel method of thickening lubricating base fluids to grease consistency.

Another object is to provide lubricating grease compositions of increased stability comprising a hyrolyzable synthetic ester oleaginous base lubricating fluid.

Another object is to provide novel grease thickeners of enhanced thickening power,

Another object is to provide a novel method of thickening an oleaginous base fluid which requires a lesser amount of thickener than heretofore.

These and other objects will become evident on consideration of the following specification and claims.

-in accordance with this invention, there are provided novelchemical compounds comprising an ortho ester of an element selected from the group consisting of A1, Si and Ti with a hydroxy-substituted fatty acid soap of a metal of Groups I-III.

Compounds of the stated nature, it has been found, can be prepared by reacting an ortho ester of aluminum silicon or titanium in a solvent with a Group I-III metal soap of a hydroXy-substituted acid.

These novel compounds have been found to be effective thickeners for oleaginous base fluids, forming greases and like thickened lubricating products. Greases comprising these novel compounds and an oleaginous base fluid, and a method of thickening an oleaginous base fluid to a grease, comprising introducing a thickening amount of the stated type of novel compound, are also provided by this invention.

It has been found that said novel compounds have a valuably potent thickening action when added to an oleaginous base fluid. Thus, for example, the ester prepared by reacting the lithium soap of IZ-hydroxystearic acid with aluminum triisopropoxide has half again as potent a thickening effect as the lithium 12-hydroxystearate thereby.

3,158,573 Patented Nov. 24, 1964 "ice soap. It requires only about /3 the amount, by weight, of this novel metal ester as of the lithium soap of hydroxystearic acid to thicken an oleaginous base fluid to the same extent.

Moreover, the present compounds of a hydroxy fatty acid having hydroxy groups blocked by esterification have enhanced stability in lubricating compositions, particu larly in lubricating compositions comprising ester type oleaginous base fluids, as compared to the soaps of hydroxy-substituted fatty acids containing a free hydroxy group.

Thus the advantages obtained by thickening an oleaginous base fluid with the novel compounds of the present invention include a reduction in the amount of thickener needed and the cost of thickening such a fluid to the desired grease consistency, and also an enhancement of the stability of the resulting grease, especially where the oleaginous base fluid is of the synthetic ester type.

A grease comprising an oleaginous base fluid and a thickening amount of a novel compound as provided by this invention is a novel valuable product adapted for use for a variety of purposes. It is especially useful where low temperature performance is required. It is also particularly valuable where a lubricant characterized by retention of substantially the same viscosity over a wide temperature range, coupled with satisfactory stability, is required, for which purpose the synthetic lubricating fluids including the ester base type are frequently used.

The nature of the presently provided novel compounds may be appreciated most readily by consideration of the method by which they may be prepared. In accordance with this invention, the stated novel compounds are pre pared by the reaction of a hydroxy-substituted fattyaoid compound in a solvent with an ortho ester of an element selected from Al, Si and Ti. The reaction taking place may be represented by the following equation, illustrating a preferred form of the practice of this invention:

(HOCHR-COO) MYX (RO).,M

[(R"O) n-mM][(O CIHRG O O) ,-MYX] where R and R are aliphatic hydrocarbon radicals containing together from 10 to 22 carbon atoms, M is a metal of Groups IIII, R" is selected from the group consisting of alkyl and alkoxyalkyl radicals of from 1 to 8 carbon atoms, M is an element selected from the group consisting of Al, Si and Ti, Y is an anion, n and m are integers, n is the valence of M, in has a value of from 1 to n and x and y are integers whose total equals the valence of M. Where more than one R"O group is present in the illustrated formulae, each R may be the same or differeat. The Groups referred to are Groups of the Periodic Table.

The first reactant shown in the above-illustrated equation is a soap of a hydroxy-substituted fatty acid, containing a total of from 12 to 24 carbon atoms. Preferably thehydroxy-substituted fatty acid will be one in which the radical represented by R in the above equation contains a chain of at least five carbon atoms. Various sources of such fatty acids are available. The most particularly preferred of these fatty acids is l2-hydroxystearic acid. Materials supplying 12-hydroxystearic acid, generally admixed with certain amounts of other fatty acid radicals, such as hydrogenated ricinoleic acid and hydrogenated castor oil fatty acids are also useful in preparing the compounds of this invention; and when reference is made herein to IZ-hydroxystearic acid or its derivatives, it is to be understood that these commercial sources of this acid are intended to be included While 12-hydroxystearic acid is the most readily available of the hydroxy-substituted fatty acids, if desired soaps of other suitable fatty acids may be employed instead. Exemplary of presently useful hydroxy-substituted fatty acids are: hydroxycapric acid, dimethylhydroxy caprylic acid, dimethylhydroxycapric acid, hydroxylauric acid, hydroxymyristic acid, hydroxypalmitic acid, hyroxyarachidic acid, hydroxybehenic acid, S-hydroxystearic acid, and so forth. Hydroxy fatty acids which are suitable also include those formed by hydroxylation of unsaturated fatty acids of the indicated chain length, effected, for example by such oxidizing agents as peracetic acid, potassium permanganate and the like; hydroxy acids prepared by cholorinating fatty acids and hydrolyzing the chloro acids; mixtures of fatty acids or the like comprising hydroxy fatty acids of the stated chain length and so forth.

In some cases it may also be suitable to employ unsaturated fatty acids which are hydroxy-substituted such as ricinoleic acid, l1-hydroxy-9-undecenoic acid, hydroxypalmitoleic acid, and so forth. It may also be possible to use poly-vic-hydroxy-substituted fatty acids such as 9,10-dihydroxystearic acid, dihydroxygadoleic acid, and so forth. However, the saturated mono-hydroxy-substituted fatty acids are preferred for use in the present invention.

These fatty acids are used, as shown in the above equation, in the form of soaps thereof, that is salts of the hydroxy-substituted fatty acids, with metals of Groups I-III.

Where the metal M is a metal of Group I, which metals have a valence of 1, the fatty acid soap will be of the formula where R and R are as defined above, and M is a metal of Group I. Soaps of this type, and particularly the lithium soaps of hydroxy-substituted fatty acids of this type, form the preferred type of hydroxy-substituted fatty acid compound used in preparing the novel compounds of this invention. The lithium soap of 12-hydroxystearic acid is especially preferred. Alternative Group I metal soaps which are within the scope of the present invention comprise sodium, potassium or like alkali metal salts of 12-hydroxystearic acid; lithium ll-hydroxystearate, lithium S-hydroxystearate, lithium hydroxypalmitate, sodium S-hydroxystearate, lithium hydroxymyristate, lithium hydroxyarachidate, sodium hydroxyenanthate, sodium hydroxypalmitate, potassium hydroxypalmitate, and so forth. The sodium salts are referred to in the art as soda base soaps, and this terminology is sometimes used herein.

Where M is a metal of Groups II or III, the formula for the fatty acid soaps may be illustrated as follows:

(H -0 HR- O 0) y-Mnm x where M is a metal of Groups H or III, and x-t-y equals the valence of the metal. Preferably y will have an average value of at least 1. Where y has a value of less than the valance of the metal, Y in the stated formula will represent an anion satisfying the residual valence of the metal. Fatty acid soaps or salts are generally prepared by reacting the fatty acid or a compound thereof such as a fatty acid ester with an inorganic compound of the salt-forming metal, such as aluminum sulfate, for example. Under commercial conditions, the stated reaction frequently fails to replace all of the inorganic radicals attached to the trivalent metal with radicals of fatty acid. Y in the above-stated formula represents groups satisfying the residual valence of the metal, other than valences satisfied by soap formation with the hydroxy-substituted fatty acid, which may be present because of this incomplete soap formation. Generally Y will represent inorganic radicals, usually of relatively low molecular weight, such as a halide ion 4- like chloride, bromide or fluoride, or an oxygen-containing radical such as hydroxide or carbonate, bicarbonate or sulfate.

Examples of presently useful soaps of a metal of Group II are the alkaline earth metal soaps such as the calcium, zinc, strontium and barium soaps of ll-hydroxystearic acid, dimethyl hydroxycaprylic acid, S-hydroxystearic acid, hydroxypalmitic acid, and so forth.

The most preferred and most common of the soapforming metals of Group III is aluminum. Illustrative of presently useful aluminum salts are aluminum tris(l2- hydroxystearate), aluminum bis(12 hydroxystearate) chloride, aluminum bis(12-hydroxystearate) hydroxide, aluminum bis(12-hydroxystearate) sulfate, aluminum mono(12-hydroxystearate) dichloride, aluminum mono- (IZ-hydroxystearate) dihydroxide, aluminum mono(l2- hydroxystearate) disulfate, aluminum tris(8-hydroxystearate), aluminum bis(l0-hydroxystearate) sulfate, aluminum tris (hydroxypalmitate), aluminum bis(hydroxypalmitate) sulfate, aluminum bis(hydroxypalmitate) hydroxide, aluminum bis(hydroxymyristate) hydroxide, aluminum bis(ltydroxylaurate) sulfate, and so forth. The corresponding soaps of other metals of Group III may be employed alternatively, if desired.

In all cases, mixtures of different soaps of Groups I-III metals with hydroxy-substituted fatty acids may be used instead of individual compounds. Also, mixed soaps of hydroxy fatty acids and unsubstituted fatty acids such as, for example, aluminum bis(12-hydroxystearate) stearate, may be used.

With respect to the second reactant employed in preparing the novel compounds of this invention, this is an ortho ester of the formula (R"O) M where R is selected from the group consisting of alkyl and alkoxyalkyl radicals of from 1 to 8 carbon atoms, M is an element selected from the group consisting of Al, Si and Ti and n is the valence of M. Generally it will have a value of more than, 1, in which case R in each of the radicals R"O present in the stated ester may be the same or different.

A first class of the said ortho esters particularly preferred in the practice of this invention are the ortho aluminates. These include, for example, aluminum trimethoxide, aluminum triethoxide, aluminum tri-npropoxide, aluminum triisopropoxide, aluminum tri-nbutoxide, aluminum triisobutoxide, aluminum triamoxide, aluminum trihexoxide, aluminum triisooctoxide, aluminum methoxide diethoxide, aluminum n-propoxide diisopropoxide, aluminum tris(2-methoxyethoxide), aluminum tris(2 -ethoxyethoxide), aluminum tris(2-butoxyethoxide), aluminum tris(2 (2 ethoxyethoxy)ethoxide), aluminum tris(2-hexoxyethoxide), and so forth. Aluminum triisopropoxide is especially preferred.

A second class of said ortho esters also of particular interest in the practice of this invention comprises ortho silicates. Tetraethyl silicate is particularly preferred. Alternatively there may be employed other esters of ortho silicic acid such as tetramethyl silicate, tetrapropyl silicate, tetrabutyl silicate, tetraamyl silicate, tetrahexyl silicate, tetraoctyl silicate, tetraisopropyl silicate, dimethyl diethyl silicate, triethyl hexyl silicate, tetrakis(2-ethoxyethyl) silicate, bis(2-methoxyethyl) diethyl silicate, and so forth.

A third element which forms ortho esters useful in the practice of this invention is titanium. Accordingly, the presently useful ortho metal esters will include titanates such as tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetrahexyl titanate, tetraamyl titanate, triethyl methyl titanate, tetrakis(2-ethoxyethyl) titanate, and so forth.

In each case, either individual ortho esters or mixtures thereof may be used in practicing the invention.

Displacing one of the ester radicals of the aforesaid ortho esters with Group I-III metal soap of a hydroxysubstituted fatty acid as hereinabove discussed in accordance with the method of this invention produces the novel chemical compounds of this invention, comprising ortho esters of an element of Groups III and IV with a hydroxy-substituted fatty acid soap of a metal of Groups I-III, as represented by the equation (HO-CHRCOO) M-Y= (RO)n [(RO) n-m M"'-][(O (IJHR C 00) --MYX] n 3 where R, R, R, M, M, Y, n, m, x and y are as defined above, and the formula on the right represents a preferred form of the novel chemical compounds provided by this invention.

As will appear hereinafter, the presently provided products also include esters in which R" of the stated formula may be replaced by another group.

The novel chemical compounds of this invention include various types, depending on the nature of the salt-forming metal and of the ester-forming element, and also depending on the ratio in which the ortho ester is reacted with the fatty acid soap.

In general, where the ortho ester is an aluminate, the product is an aluminate ester of the hydroxy fatty acid soap. For example, the product may be an aluminate ester of lithium hydroxystearate.

Similarly, using an ortho ester of silicon or titanium, the products are, respectively, silicate and titanate esters of hydroxy fatty acid soapsv As will be appreciated from the following detailed discussion, the. term, an aluminate ester of a fatty acid soap,'.is inclusive of various individual aluminate esters thereof, such as the dialkoxy aluminate monoester, the monoalkoxy aluminate diester, and the aluminate triester. of the soap. The terms, a silicate or titanate ester of these soaps, are similarly inclusive.

Those skilled in the art will appreciate that the transesterification reaction illustrated above may produce a mixture of such mono-, diand triesters, rather than an individual ester, particularly where the diand triesters are. being made. Such mixtures are useful as grease thickeners in the practice of this inventiorn and are specifically contemplated as included among the presently provided novel products.

Referring to specific products and compounds provided hereby, when M in the above formula is a metal of Group I and from 1 to n moles of a soap of such metal is reacted with an ortho ester, where n is the valence'of the metal or metalloid element in the ortho ester, the products will have the formula R" o ..-...M' ocn a co0M where R", R, R, M, n, m and M; are as hereinabove defined.

-- When M is aluminum, these compounds may be designated asaluminate esters of Group I metal hydroxy fatty acid salts. When the fatty acid soap and aluminum ortho ester react ina 1:1' molar ratio, In in the above formula has a value of 1 and n-m, a value of 2. These products are exemplified by lithium l2-hydroxystearate diisopropoxy aluminate ester, lithium l2-hydroxystearate diethoxy aluminate ester, lithium l2-hydroxystearate dibutoxy aluminate ester, lithium l2-hydroxystearate dihexoxy aluminate ester, lithium 12-hydroxystearate bis(2-ethoxyethyl). aluminate ester, lithium l2-hydroxystearate ethoxy butoxy aluminate ester, the diisopropoxy aluminate ester of the soda base soap of l2-hydrox stearic acid, potassium IZ-hydroxystearate diisopropoxy aluminateester, the diisopropoxy aluminate ester of the soda base soap of S-hydroxystearic acid, the bis-(Z-eth oxyethyl) aluminate ester of the soda base soap of 8- hydroxystearic acid, lithium hydroxycaprate diisopropoxy aluminate, lithium S-hydroxystearate diisopropoxy aluminate, lithium hydroxyarachidate diisopropoxy aluminate, and so forth. Reaction of two moles of the fatty acid soap with one mole of the aluminate ester provides diesters such as the isopropoxy aluminate diester of lithium 12-hydroxystearate, the isopropoxy aluminate diester of the soda base soap of IZ-hydroxystearic acid, the Z-methoxyethyl aluminate diester of lithium l2-hydroxystearate, the isopropoxy aluminate diester of lithium hydroxylaurate, and the butoxy aluminate diester of lithium hydroxypalmitate. When an aluminum ortho ester reacts with three moles of the fatty acid soap, so that all the R"O groups of the ortho ester are removed, In in the above formula is 3, and rz-m is 0. The products are triesters such as the aluminate triester of lithium l2-hydroxystearate, the aluminate triester of lithium hydroxylaurate, the aluminate triester of the soda base soap of l2-hydroxystearic acid, and so forth.

An aluminate ester of lithium hydroxystearate, es pecially such an aluminate ester product comprising a major proportion of the aluminate triester of lithium hydroxystearate, is a preferred product in this class of presently provided novel products.

Variation in the individual compounds produced, depending on the ratio of fatty acid soap to ortho ester, similarly occurs when the present compounds are produced from ortho esters of the other elements. Thus, the presently provided silicate esters of Group I metal soaps include 1:1 molar ratio products such as lithium IZ-hydroxystearate tributoxy silicate ester, lithium hydroxybehenate triethoxy silicate ester, lithium dimethylhydroxycaprylate trihexoxysilicate ester, potassium l2- hydroxystearate triethoxy silicate ester, the diethoxy butoxy silicate ester of the soda base soap of 8-hydroxystearic acid, lithium 12-hydroxystearate tris(2- ethoxyethyl) silicate ester, and so forth. A 1:2, 1:3, or 1:4 molar ratio gives products such as the diethoxy silicate diester of lithium 12-hydroxystearate, the monoethoxy silicate triester of lithium 'l2-hydroxystearate, the

silicate tetraester of lithium l2-hydroxystearate, the diethoxy silicate diester of the soda base soap of 12-hydroxystearic acid, the diethoxy silicate diester of lithium hydroxypalmitate, the mono(2-butoxyethyl) silicate triester of potassium l2-hydroxystearate, and so forth. The titanate esters include, for example, lithium 12-hydroxystearate trimethoxy titauate ester, the triethoxy titanate ester of the soda base soap of l2-hydroxystearic acid, lithium IZ-hydroxystearate tris(Z-ethoxyethoxy)titanate, and lithium lZ-hydroxystearate triisopropoxy titanate ester; the dimethoxy titanate diester of the soda base soap of hydroxylauric acid, the diisopropoxy titanate diester of lithium l2-hydroxystearate, and diisobutoxy titanate diester of the soda base soap of hydroxymargaric acid; the monoisopropoxy titanate triester of lithium l2- hydroxystearate, the monoethoxy titanate triester of lithium l2-hydroxystearate, the monoethoxy titanate triester of the soda base soap of hydroxymyristic acid, the titanate tetraester of the soda base soap of hydroxyarachidic acid, the titanate tetraester of lithium 12-hdroxystearate, andso forth.

Referring to the esters of the soaps of hydroxy-substituted fatty acids with Group II and Group III metals provided by this invention, here again the individual products depend on the ratio in which the reactantscombine. Preferably, in accordance with this invention, each of the hydroxy groups present in the starting material consisting of a hydroxy fatty acid soap will be esterified by reaction with the ortho ester. The ratio of reactants, in terms of the ratio of hydroxy fatty acid radicals present in the soap to ortho ester molecules, may vary from 1:1 to 3:1 or 4:1. As will be appreciated, a divalent metal soap will contain two hydroxy fatty acid radicals and a 1:1 ratio of such a soap to ortho ester will require 2 moles of ortho ester per mole of soap to provide one ortho ester molecule per fatty acid hydroxy radical. For a soap of a Group III metal like aluminum tris(hydroxy fatty acid) soaps, three moles of ortho ester per mole of the soap is needed to produce a 1:1 ratio.

On reaction in such a 1:1 ratio, esterification of the hydroxy groups can occur by displacement of a single one of the ester groups of the ortho ester, giving products of the structure [(R O)Z' M ][(O(FI RCOO)y l\I Y3] R 3 where z is 2 when M is trivalent, and 3 when M is tetravalent, and R", M, R, M, m, x and y are as defined above. These 1:1 esters may be represented as shown in the formula, using an aluminate ester of a calcium soap as an example, as

[(R )z I h Ji/z As will be evident, the molecular formula corresponding to this will be (RO) Al-OC[HRCOOCaOO(FRCHO-AI(OR) and the products are bis(diallroxy aluminate) esters of calcium hydroxy fatty acid soaps.

At a ratio of 2 or more hydroxy fatty acid radicals per molecule of ortho ester, to esterify each of the hydroxy groups requires that two or more ester groups be displaced from each ortho ester molecule by hydroxy fatty acid radicals. Depending on whether these are the radicals of the same molecule of soap, or of different soap molecules, the resulting structure may vary. For example, using a 2:1 ratio in reacting a calcium soap with an aluminate ortho ester to produce an ester represented in accordance with the above formula as [(R"o)A1][ ocI-1nooonoal T t E(=1) the product may have a cyclic structure I RCHOAl-O--OHR R/O O I|t J OCaOC or a polymeric structure containing the repeated units Where reaction takes place at the maximum ratio, which is 3:1 for trivalent metal ortho esters, and 4:1 for tetravalent metal ortho esters, the products may have even more complex structures. In referring to the generic product formula given herein, it is not intended to restrict the present products to any specific structure.

Referring then to aluminate esters of Group II metal soaps, the 1:1 ratio products will include calcium 12-hydroxystearate bis(diisopropoxy aluminate ester), zinc 12- hydroxystearate bis(diisopropoxy aluminate ester), strontium 12-hydroxystearate bis(diisopropoxy aluminate ester), barium 12-hydroxystearate bis(dibutoxy aluminate ester), barium hydroxylaurate bis(dimethoxy aluminate ester), calcium S-hydroxystearate bis(dibutoxy aluminate ester), zinc hydroxymyristate bis(diethoxy aluminate ester), calcium l2-hydroxystearate bis(diisoheptoxy aluminate ester), zinc 8-hydroxystearate bis[bis(2-etl1- oxyethoxy) aluminate ester], and so forth.

Where the aluminum ortho ester is reacted with the Group II metal soap in a ratio providing two moles of fatty acid hydroxyl groups per mole of ortho ester, the aluminate esters provided may be designated as monoalkoxy aluminate diesters. Exemplary of these are the mono-isobutoxy aluminate diester of calcium 12-hydroxystearate, the mono-isopropoxy aluminate diester of zinc hydroxylaurate, and so forth. Where the ratio is 3:1, the esters obtained include, for example, alumiuates which may be referred to as triesters such as the aluminate triester of calcium 12-hydroxystearate, the aluminate triester of barium hydroxymyristate, the aluminate triester of zinc 12-hydroxystearate, and so forth.

Silicate esters of Group II metal soaps provided by this invention include those wherein from 1 to 4 moles of fatty acid hydroxy groups per mole of silicate ortho ester are reacted to form the present novel products. Exemplary of the 1:1 ratio products are, for example, barium 12-hydroxystearate bis(triethoxy silicate ester), zinc 12- hydroxystearate bis(triethoxy silicate ester), strontium 12-hydroxystearate bis(triethoxy silicate ester), zinc hydroxycarnaubate bis(triethoxy silicate ester), calcium 12- hydroxystearate bis[tris(2-ethoxyethoxy) silicate ester], zinc 8-hydroxystearate bis(trioctoxy silicate ester), and so forth. Where the ratio is 2:1, 3:1 or 4:1, the compounds provided by this invention include, for example, the diethoxy silicate diester of barium 12-hydroxystearate, the dibutoxy silicate diester of calcium 12-hydroxyst arate, the diethoxy silicate diester of calcium hydroxypalmitate, the monethoxy silicate triester of zinc 12-hydroxystearate, and the like.

Exemplary of titanate esters of divalent Group II metal soaps of hydroxy-substituted fatty acids provided by this invention are, calcium 12-hydroxystearate bis(triethoxy titanate ester), zinc hydroxylaurate bis(tripropoxy titanate ester), calcium l2-hydroxystearate bis(tributoxy titanate ester), zinc 12-hydroxystearate bis(tripropoxy titanate ester), the bis(Z-ethoxy) titanate triester of zinc 8-hydroxystearate, the titanate tetraester of calcium 12- hydroxystearate, and so forth.

Coming now to the products of reaction of the ortho esters with soaps of hydroxy-substituted fatty acids with metals of Group 111, one preferred class of compound of this type is the aluminum-aluminum system, provided by reacting an aluminate ortho ester with an aluminum soap of a hydroxy-substituted fatty acid. Exemplary of these compounds are a 1:1 ratio product such as aluminum tris(12-hydroxystearate) tris(diisopropoxy aluminate ester) of the formula Use of commercial aluminum 12-hydroxystearate wherein valences of the soap-forming aluminum atom not bonded to the carboxyl radical of the hydroxy-substituted fatty acid are satisfied by anions such as inorganic groups like hydroxide, sulfate or the like, may give mixtures of the above-illustrated compound with compounds where an average of from 1 to 2 of the valences of the saltforming aluminum radical are satisfied by anions such as sulfate groups. These mixtures and aluminum 12- hydroxystearate (diisopropoxy aluminate ester) disulfate or like ester soaps included therein are also included among the novel products of this invention, and references to aluminum hydroxy fatty acid esters herein should be understood as including all such products.

Additional aluminum-aluminum systems provided in accordance with this invention comprise for example, 1:1 ratio products like aluminum 12-hydroxystearate dimethoxy aluminate ester, aluminum hydroxylaurate diethoxy aluminate ester, aluminum hydroxybehenate dibutoxy aluminate ester, aluminum hydroxypalmitate dihexoxy aluminate ester, aluminum 12-hydroxystearate dioctoxy aluminate ester, aluminum IZ-hydroxystearate bis(2- methoxyethoxy) aluminate ester, and so forth; 2:1 ratio products such as the monoisopropoxy aluminate diester of aluminum IZ-hydroxystearate; and 3:1 ratio products such as the aluminate triester of aluminum 12-hydroxystearate, the aluminate triester of aluminum dimethylhydroxycaprate, and so forth.

Silicate ester-s of Group III salts of hydnoxy-substituted fatty acids provided by this invention include, for example, aluminum 12-hydroxystearate triethoxy silicate ester, aluminum hydroxyarachidate tripropoxy silicate ester, the dibutoxy silicate diester of aluminum hydroxydimethylcaprylate, the tris(2-ethoxyethoxy) silicate monester of aluminum 8-hydroxystearate, the silicate tetraester of aluminum l2-hydroxystearate, and so forth. Other esters of salts of Group III metals provided hereby include aluminum 12-hydroxystearate tris [2-(2-ethoxyethoxy)ethoxy] titanate ester, aluminum 12-hydroxystearate triethoxy titanate ester, the dibutoxy titanate diester of aluminum 12- hydroxystearate, the titanate tetraester of aluminum hydroxylaunate, and so forth.

A general formula for the products provided by this invention, including the above as well as additional esters described hereinafter, is as follows:

where a a and 11 are integers each selected individually from and 1, a +a +a ='nm, R R and R are each selected individually from the group consisting of hydrocarbon and halo-hydrocarbon radicals of from 1 'to 18 carbon atoms, and M, M, R, R, Y, m, n, x and y are as hereinabove defined.

It has been stated above that the present esters of hydroxy fatty acid soaps are preferably made in accordance With this invention by tr-ansesterification of an ortho ester of the formula (R"O) M, where R" is alkyl or alkoxyalkyl of 1 to 8 carbon atoms, and M is Al, Si or Ti, with the fatty acid soap.

By transesterifying such an ortho ester with the hydroxy fatty acid soap and also with one or more alcohols in which the radical attached to the alcohol hydroxy group is hydrocarbon, hydrocarbonoxyhydrocarbon, or halogenated hydrocarbon or hydrocarbonoxyhydrocarbon of 1 to 18 carbon atoms, esters of the above-illustrated formula may be produced. g

The stated alcohol may be a hydroxy-hydrocarbon, including saturated aliphatic alcohols such as higher alkanols like isooctyl, nonyl, hexadecyl and octadecyl alcohols, and cycloalkanols like cyclohexanol; glycols like ethylene glycol; and aromatic, including aralkyl and alkaryl, alcohols like phenol, benzyl alcohol, and so forth. It may be hydrocarbon-oxy-hymocarbon, that is, an ether alcohol, such as diethylene glycol butyl ether, guaiacol, p-phenoxyphenol,'and so forth. The lower alkanols and alkoxy-alkanols, like ethanol and Z-ethoxyethanol, could be used, but since the ort-ho esters already contain lower allroxy radicals, generally no advantage would be gained.

The stated alcohol can also be a halogenated derivative of one of the stated types of alcohols. V The halogen present therein will prefer-ably be relatively stable and inert; it may be bromine, chlorine or fluorine. H-alogenated alcohols wherein the hydrocarbon radical contains few or no hydrogen atoms, are preferred. Exemplary of lower haloalkanols of this class are perfluoroethanol, perchloroethanol, perbromoethanol, trifiuoroethanol, t-rifiuorobromochloroethanol, tetrafiuoropropanol, pentafluoropropanol, perfluoropropanol, perfluorobutanol, perchlorocyclopentanol, perfluorohexanol, decafluorohexanol, nonafiuoro-Z-ethoxyethanol, and the like.

Illustrative of the higher haloalkanols, which we preferred in the present connection, are heptanols substituted by from 12 to 15 fluorine atoms, nonanols substituted the ester radicals of the original ortho ester may remain by from 16 to 19 fluorine atoms, undecanols substituted by from 20 to 23 fluorine atoms, tridecanols substituted by from 24 to 27 fluorine atoms, perfiuorohexadecanol, perchlorinated and perfluorinated diethylene glycol butyl ether, perbromohexanol, and so forth. Cycloalkanols such as perchlorocyclohexanol may also be used, as may aromatic alcohols such as pentachlorophcnol and the like.

Referring to the products obtained in this embodiment of the invention, when the stated alcohol an alkanol (including ether alkanols) and it is reacted with an aluminate ester of a hydroxy fatty acid soap, the product is an alkoxy aluminate ester of the fatty acid soap. For example, it maybe an isooctoxy aluminate ester of lithium hydroxystearate, a hexadecoxy aluminate ester of the soda base soap of hydroxystearic acid, a 2[2-(2-butoxy) ethoxy] ethoxy alumin-ate ester of lithium hydroxystearate, and so forth. 7

Similarly, combining such an alkanol with products such as the titanate and silicate esters of hydroxy fatty acid soaps as described above yields products such as an octoxy silicate ester of lithium hydroxystearate, a dodecoxy silicate ester of lithium hydnoxystearate, a decoxy titanate ester of lithium hydroxystearate, an octadecoxy b-orate ester of lithium hydroxystear ate, and so forth.

Additional products of hydroxy-hydrocarbons and ether alcohols provided hereby include, for example, a cyclohexoxy aluminate ester of lithium hydroxystearate, a glycol diester of an aluminate ester of lithium hydroxystearate, a phenoxy aluminate ester of the soda base soap of hydroxystearic acid, a benzyloxy silicate ester of lithium hydroxypalmitate, an isopropoxyphenoxy silicate ester of lithium hydroxystearate, and so forth.

Referring to products obtained from haloalkanols, these include as preferred products fluoroalkoxy esters such as a tritiuoroethoxy aluminate ester of lithium hydroxystear-ate, a heptafluoro-2-methoxyethoxy aluminate ester of sodium hydrorrystearate, a perfluoropentoxy silicate ester of lithium hydroxystearate, a hexadecaiiuorononoxy silicate ester of aluminum hydroxystear-ate, a perfiuorobw t-andioxy silicate ester of lithium hydroxystearate, a dodecafluoroheptoxy titanate ester of lithium hydroxystearate, a dodecafiuoroheptoxy aluminate ester of lithium hydroxystearate, a perfluorotridecoxy aluminate ester of aluminum hydroxystearate, and so forth; as Well as other haloalkoxy esters such as tribromoethoxy aluminate ester of sodium hydroxystearate, a perchlorocyclohexoxy aluminate ester of lithium hydroxystearate, a perbromoethoxy silicate ester of lithium hydroxystearate, a broomchlorodecoxy silicate ester of lithium hydroxystearate, ,a per'oromohexoxy titanate ester of aluminum hydroxystearate, and so forth.

Illustrative of products obtainable from halogenated aryl alcohols are haloaryloxy esters such as a pentachlorophenoxy aluminate ester of lithium hydroxystearate, a pentachlorophenoxy silicate ester of lithium hydroxysteal-ate, a trifiuoromethylphenoxy silicate ester of aluminurn hydroxystearate, a phenyltetrafluoroethoxy silicate ester of lithium hydroxystearate, a pentacblorophenoxy titanate ester of lithium hydroxystearate, and the like.

The stated alcohol may provide from 1 to all of the ortho ester radicals not esterified by the hydroxy fatty acid soap. Where it does provide less than all, one or two of present in the product. For example, a fluoroheptoxy aluminate ester of lithium hydroxystearate includes the di- (fiuoroheptoxy) aluminate and mono(fluoroheptoxy) mono-substituted (such as mono-isopropoxy) alurninate mono-esters of lithium hydroxystearate, as well as the mono(fiuoroheptoxy) aluminate diester of lithium hydroxystearate. It is to be understood that the preceding list of illustrative esters includes each of such individual species.

Considering now the preparation of the above-discussed novel compounds, the method provided by this invention comprises contacting the selected ortho ester of an element selected from Al, Si and Ti with the selected hydroxy-substituted fatty acid soap of a metal of Groups I-lll, as set forth hereinabove, in a solvent. The ratios in which the ortho ester and the hydroxy-substituted fatty acid soap are contacted will, as will be evident from the preceding discussion, depend on the nature of the product desired. At least suflicient ortho ester will be present to permit esterification of each of the hydroxy groups present in the fatty acid radicals of the hydroxy fatty acid soap. Thus, at least about one-third mole of an aluminum ortho ester and at least about one-fourth mole of a silicon or titanium ortho ester will be employed per mole of hydroxy fatty acid radicals. Preferably, to provide the 1:1 ratio compounds discussed above, the reaction mixtures will cornprise about 1 mole of the ortho ester per mole of hydroxy fatty acid radical. In calculating these ratios, a mole of a soap containing one hydroxy fatty acid radical per atom of soap-forming metal will be regarded as providing one mole of hydroxy fatty acid radical, one mole of a soap containing two hydroxy fatty acid radios s per atom of the soap-forming metal will be regarded as providing two moles of hydroxy fatty acid, and so forth.

The solvent to be employed in preparing the novel compounds of this invention should be a substantially inert fluid which dissolves or is miscible with the reactants employed. Suitable solvents, for example, comprise an aromatic hydrocarbon such as toluene or xylene, an aliphatic hydrocarbon such as a petroleum fraction or cyclohexane, or a non-hydrocarbon solvent such as morpholine, dimethyl formamide, pyridine, or the like. Generally it is preferred that the solvent have a moderately high boiling point, on the order of about 100 C. or above.

To effect formation of the presently provided novel compounds, the reactants will be contacted in the solvent for a time and at a temperature sufficient to permit at least a substantial proportion of the fatty acid hydroxyl radicals to become esterified by the ortho ester. This reaction may take place at room temperature or below. It can and generally will be accelerated by heating. Temperatures to be employed in such case may range from just above about room temperature to any temperature below the decomposition temperature of the reaction mixture components.

The reaction by which the hydroxy group of the hydroxy-substituted fatty acid salt is esterified by the ortho ester involves displacement of an alkoxy group from the ortho ester. This alkoxy group forms an alcohol. The reaction may accordingly advantageously be conducted at a temperature such that the alcohol formed by this transesterification is evolved from the reaction mixture. By measurement of the amount of such alcohol evolved, the reaction can be followed so as to control the extent of esterification of the metal ortho ester by the hydroxy-substituted fatty acid.

Operation at atmospheric pressure is ordinarily preferred but elevated or decreased pressure can be used where necessary. Generally the pressure is desirably such that the alcohol formed is allowed to distill off but sufficient to maintain the reactants in the liquid phase.

Catalysts are not necessary for the present reaction but may sometimes be used advantageously. Useful catalysts for transesterification are generally bases. The ortho ester may be sufficiently basic to catalyze the reaction itself. Catalysts which may be used include alkoxides of alkali metals, such as sodium methoxide, potassium methoxide, sodium ethoxide and so forth; and alkalies such as sodium, lithium and potassium hydroxide, sodium bicarbonate, or the like.

During the heating of the reaction mixture, the product comprising the ester of the soap of the fatty acid separates. The present products are substantially insoluble in a solvent like xylene, and the xylene can be separated therefrom to a major degree by simply pressing, for

example. Isolation of the product can be effected by evaporating off the solvent, which may be done under vacuum, for example. The isolated products are generally crystalline materials, which are adopted for incorporation into an oleaginous base fluid, as set forth hereinafter.

While the foregoing is the preferred method of synthesis of these novel compounds provided by this invention, it will be appreciated that alternative procedures may sometimes be followed. For example, the ortho ester may be first reacted with a hydroxy-substituted fatty acid compound such as the hydroxy-substituted fatty acid itself, or an ester thereof, to esterify the hydrox group, and the resulting ester thereafter converted to a soap by reaction with a soap-forming metal compound such as a metal hydroxide.

While pro-forming of the complex soap is the preferred procedure, it is to be noted that the ester soap may also be formed in a lubricating oil base in situ, particularly when non-saponifiable inert oils such as mineral oils or non-hydrolyzable synthetic oils are used. For this purpose, the reactants will be dissolved in a portion of the lubricating oil base and reacted at the necessary temperature. When the reaction is complete, additional lubricating oil fluid may be added and the mixture may be milled or otherwise treated to disperse the ester soaps through the whole mixture to provide a grease.

In practicing the embodiment of this invention using an alcohol as a reactant, in addition to the ortho ester and hydroxy fatty acid soap, it is preferred to form the ortho ester of the hydroxy fatty acid soap first, and then to react it with the alcohol. Advantageously, the alcohol will simply be added to the hydroxy fatty acid soap ester prior to its isolation from the reaction mixture. The amount of alcohol recruired to displace all the alkoxy radicals from the soap ester will equal nm moles per mole of soap ester, where n and m have the values stated above. Preferably, the alcohol:soap ester molar ratio will be about 1:1, but it may range from 0.1:1 up to 10:1. Reaction conditions substantially as described above may be used to effect reaction of the alcohol with the ester of the soap, and isolation of the product can also be accomplished similarly.

To provide the lubricating grease compositions of this invention where the ester soap is not formed in situ in the oleaginous base fluid in which it is to be used, it will be dispersed therein, generally after isolation from the solvent in which it is prepared, in grease-making proportions. The concentration required to thicken the lubricating base fluid to a grease will vary, depending on the selected compound. In accordance with this invention, it may be as low as about 0.5% by weight of the total grease, and still give effective thickening. Proportions up to about or even by weight of the total, of thickener in a lubricating base fluid are frequently used. Generally with the particularly effective thickeners of this invention, a proportion up to about 15% will be found satisfactory to provide grease consistencies. However, higher concentrations may be used if desired.

It may be advantageous to prepare concentrates of the ester soaps, adapted for dilution at the point of use. Such concentrates will generally comprise a lubricating base fluid as a liquid medium for the thickener, but the liquid medium may instead be another fluid compatible with the type of lubricating base fluid with which it is to be combined if desired, such as an alcohol or the like. The concentration of the presently provided novel thickener in a concentrate composition will generally be at least about 40% by weight of the total, and may be as high as or even by weight of the total if desired.

The new ester soaps of this invention may also be combined with conventional soap thickeners. In such cases, the novel ester soaps provided hereby should preferable comprise at least one-third of the total soap and 13 thus comprise at least about 0.150.20% by weight of the grease.

Methods of dispersing thickeners in lubricating base fluids to provide greases are well known in the art, and conventional methods therefor may be used in employing the compounds of this invention as thickeners.

The lubricating grease compositions provided in accord- I ance with this invention will comprise an oleaginous base fluid compounded with a thickening amount of one or more of the ester soaps provided hereby.

The oleaginous base used in the compositions may be selected from a wide variety of natural or synthetic lubricant oils. Thus for example, natural oils can advantageously be employed. Illustrative of such natural oleaginous bases are mineral oils such as naphthene and paraflin base oils, vegetable oils such as cotton seed oil and castor oil; animal and marine oils such as sperm whale oil, lard oil, blown fish oil and degras; and mixtures thereof. Of the natural oil bases, mineral oils are preferred. A typical mineral oil base for extreme pressure lubrication will be characterized by a viscosity of 35-350 Saybolt Universal Seconds at 210 F., a viscosity index in the range of from 25 to 150, and a flash point of between about 275 and 600 F.

Polyorganosiloxanes, also known as silicones, or silicone polymers, comprise one class of synthetic lubricant bases of commercial importance which may be improved in properties to a substantial degree by modification in accordance with this invention. Polysiloxanes are compounds comprising essentially silicon atoms connected to one another by oxygen atoms. In liquid polyorganosiloxanes, or silicones, of the lubricating oil viscosity range, a preponderant number of the remaining valences of the silicon atoms were satisfied by the substitution thereon of organic radicals, attached by a carbon-to-silicon bond. Examples of such organic radicals are aliphatic radicals including alkyl radicals such as methyl, ethyl, propyl, butyl, and so forth; alicyclic radicals such as phenyl, cyclohexyl, diphenyl, anthracyl, naphthyl, and

utility for lubricating purposes are silicones in which the silicon atoms are substituted by two different organic radicals, e.g., methyl and phenyl radicals. Especially effective properties have been obtained when the organic radicals substituted on the silicon atoms in the silicone polymers are in turn substituted by halogen atoms, espe cially chlorine atoms. Thus for example, the silicone may be substituted by chlorophenyl radicals such as dichlorophenyl, 'trichlorophenyl and tetrachlorophenyl radicals, other valences of the silicon atoms being satisfied by the hydocarbon radicals such as methyl radicals or the like. intended for use as oleaginous bases will desirably contain an average of from 1.9 to 2.67 organic groups per silicon atom. Remaining valences, if any, of the silicon atoms may be satisfied by radicals attached to the silicon atoms in the compounds from which the silicone polymers are prepared, such as hydrolyzable organo-substituted silanes; or by the produce of hydrolysis of such radicals, suchas hydroxide radicals.

Another class of synthetic oleaginous bases of particular interest in the practice of the present invention comprises organic polyesters. On the one hand, these may comprise esters of polycarboxylic acids, such as dicarboxylic acid diesters. Thus for example, such synthetic ester lubricants may have the general formula 'R(COOR (COOR where R is an aliphatic or cycloaliphatic hydrocarbon radical of from 2 to 8 carbon .atoms and R and R are the same or different and are branched chain alkylor alkyl-substituted cycloalkyl radicals of at least 4 carbon atoms. Such esters may be de- As is well known in the art, the silicones I rived from succinic, maleic, pyrotartaric, 'glutaric, adipic, pimelic, suberic, azelaic, sebacic, pinic, thiopropionic or oxypropionic acids or the like, specific esters of this nature including for example di(l-methyl-4-ethyloctyl)glutarate, di(2-ethylhexyl)oxydibutyric acid, di(2-ethylhexyl) adipate, di(3 methylbutyl) azelate, di(2 ethylhexyl)azelate, di(2 ethylheXyDsebacate, di(3,5,5 trimethylhexyl)sebacate, di(2 ethylhexyl)maleate, di- (methylcyclohexyl)adipate, 2-ethylhexyl 1--nethylhexyl sebacate and the like. Alternatively, instead of derivation from a polycarboxylic acid, the polyester synthetic oleaginous bases may be produced by reacting a polyhydric alcohol with a monocarboxyl-ic acid. Thus for example, a polyhydr-ic alcohol such as ethylene glycol or pentaerythritol is esterified with an acid of relatively long chain length such as caproic, pelargonic, capric, lauric, myristic, palmitic or stearic acid, to produce a polyester of lubricating oil viscosity. Specific examples of such polyesters derived from polyols are pentaerythritol tetrapelargonate, pentaerythritol tetracaprate, pentaerythritol tetrapflmitate, pentaerythritol tetrastearate, ethylene glycol divalerate, diethylene glycol dicaprate, propylene glycol dicaprylate, and so forth. Another type of synthetic polyester lubricants which may be used as oleaginous bases in accordance with this invention will be complex esters obtained by esterifying a polycarboxylic acid with a diol, together with a monohydric alcohol and/or a monocarboxylic acid. Thus, complex esters which may be employed as oleaginous bases may be obtained by esterifying one mole of a dicarboxylic acid with 2 moles of a glycol and 2 moles of a monocarboxylic acid; or by esterifying one mole of a dicarboxylic acid with one mole each of a glycol, a monocarboxylic acid and a mono hydric alcohol. Specific examples of a suitable complex ester are the ester prepared from one mole of ethylene glycol, two moles of sebacic acid and two moles of Z-ethylhexanol; and the ester prepared from one mole of triethylene glycol, one mole of adipic acid, one mole of n-caproic acid and one mole of Z-ethylhexanol.

In addition to the above-mentioned classes of synthetic lubricating base stocks comprising types of present major commercial importance, there are a number of other oleaginous bases which can be used if desired in the practice of this invention. Thus for example, such lubricant bases may comprise hydrocarbon oils prepared by polymerization of unsaturated hydrocarbons. Polyethers of the nature of high molecular weight polyoxyalkylene compounds, derived, for example, from ethylene oxide, propylene oxide and the like substances, form another useful class of lubricant bases, and similarly, there may be employed oleaginous bases of related structure, such as propylene oxide-tetrahydrofuran copolymers, and

polyaryl ethers. Besides the silicones discussed above, additional silicon derivatives of interest in this connection comprise silanes, silphenylenes, organosilicates and disiloxanes such as hexaalkoxydisiloxanes of lubricating oil viscosity. Other synthetic oleaginous bases which may be mentioned include fluorocarbon oils such as periiuorinated petroleum oils; tetra-substituted ureas; and esters such as dimethylcyclohexyl phthalate, trioctyl phosphate; and similar fluids adapted for lubricant applications.

Mixtures of oleaginous bases may sometimes be preferred to any single lubricant fluid, and are included inthe scope of this invention. Other conventional grease additives such as anti-oxidants, extreme pressure agents, structure stabilizers or viscosityimprovers and so forth may also be included with the compounds of this invention.

The invention is illustrated but not limited by the following examples.

Example I 1228 grams (4 moles) of lithium hydroxystearate, 832

and 5 grams of sodium methoxide are mixed in a 3-necked 15 flask. This mixture is heated with rapid agitation to a pot temperature of 140 C. The reaction mixture is held at 140 C. until 235 cc. of distillate, boiling at 78-82 C., is collected. The pot contents are then transferred to a resin kettle, and stripped of solvent over a steam bath at 1.0 mm. pressure. The residual solid is dried in a forced draft oven at 250 F. and ground to a powder. The product is a silicate ester of lithium hydroxystearate, comprising lithium hydroxystearate triethoxy silicate ester. It is a white solid melting at 200 C. A yield of 1236 grams (63.5% of theory) is obtained.

Example II 462 grams (0.5 mole) of commercial aluminum hydroxystearate, comprising aluminum tris(12-hydroxystearate), 312 grams (1.5 moles) of tetraethyl silicate, 4800 ml. of xylene and 1.6 grams of sodium methoxide are mixed in a 3-necked flask and heated to a pot temperature of 125 130' C. 87 cc. of distillate is evolved and collected during a 5 hour period. The resultant mixture is stripped of Xylene over a steam bath at 0.1.5 mm. pressure. The solid residue is dried in a forced draft oven at 250 F. A yield of 519 grams (73.5% of theory) of a silicate ester of aluminum hydroxystearate, comprising aluminum tris(hydroxystearate) tris(trietlxy silicate ester), is obtained, as a white solid melting at 262 C.

Example III 277 grams (0.3 mole) of aluminum hydroxystearate, as described in Example ll, 187 grams (0.9 mole) of tetraetnyl silicate, 2800 ml. of xylene and 1.0 gram of sodium mothoxide are mixed in a 3-necked flask and heated to a pot temperature of 125-130 C. 47 cc. of distillate is evolved and collected in a two hour period. 896 grams (2.7 moles) of a dodecafiuoroheptyl alcohol is added and the heating is continued at 125-130 C. until an additional 13-0 cc. of distillate is removed. The resultant material is filtered. The filtrate is stripped of volatiles over a steam bath at 0.5-1.0 mm. pressure. The residue is then dried in a forced draft oven at 250 F. The yield is 228 grams (20% theory) of a fiuoroheptoxy silicate ester of aluminum hydroxystearate, comprising aluminum tris(h droxystearate) tris[tris(dodecafluoroheptoxy)silicate ester], melting at 239 C.

Example 1V 184.2 grams (0.6 mole) of lithium hydroxystearate, 42.6 grams (0.15 mole) of tetraisopropyl titanate, 2000 ml. of xylene and 0.5 gram of sodium methoxide are mixed in a S-neclred flask. The mixture is heated to 125 C. while agitating vigorously. 45 cc. of distillate is removed at a temperature of 80-85" C. over a two hour period. After cooling, the reaction mixture is poured into 2000 ml. of acetone. The white preci itate is filtered oil and dried in a forced drafit oven at 220 F. The product is a titanate ester of lithium hydroxystearate, comprising the titanate tetraester of lithium hydroxystearate. It is a White crystalline solid melting at 270 C. A yield of 194 grams (97.5% of theory) is obtained.

Example V 154 grams (0.15 mole) of aluminum hydroxystearate, as described in Example H, 91.8 grams (0.45 mole) of aluminum triisopropoxide, 3000 cc. of xylene and 0.2 gram of sodium methoxide are mixed in a 3-neclred flask and heated to 128 C. 40 cc. of distillate is evolved and collected over a two hour period at a vapor temperature of 82 C. The solvent is then stripped off over a steam bath at 5 mm. pressure. The residue is dried in a forced draft oven at 250 F. 175 grams (80% of theory) of an oil-white solid is obtained. The product is an aluminate ester of aluminum hydroxystearate, omprising the aluminum tris(hydroxystearate) tris(diisopropoxy aluminate ester) l 6 Example VI 921 grams (3.0 moles) of lithium hydroxystearate, 204 grams (1.0 mole) of aluminum triisopropoxide and 4500 ml. of xylene are mixed in a S-necked flask and gradually heated to 150 C. 225 cc. of isopropyl alcohol is evolved and collected over an 8-hour period. The reaction is then stripped of xylene over a steam bath at 0.2 1.0 mm. pressure. The product is finally dried in a forced draft oven at 225 F. A yield of 933 grams (99% of theory) of aluminate ester of lithium hydroxystearate, comprising the aiuminate tricster of lithium hydroxystearate, m. 274 C., is obtained.

Example VII Fourteen grams of the product of Example VI and 186 grams of naphthenic mineral oil (150 Saybolt Universal Seconds at 210 F.) are mixed, cold, and then heated to about 200 C. to produce a clear solution. This solution is stirred while it is cooled to room temperature, and the resulting grease is milled twice in a Morehouse Mill to homogenize it.

The grease so produced, which contains 7%, by weight of the total, of the novel thickener produced as described in Example VI, has the following properties:

Penetration (ASTM)270 Dropping point3 F.

This falls within the range defined as a #2 grease on the National Lubricating Grease Institute scale. Such a grease is suitable for lubricating systems operating at relatively moderate speeds and loads, such as vane pum s, serving machines, and the like. Using a heavier oil, a #2 grease can be produced which is suitable for use at higher loads.

To produce a #2 grease using lithium hydroxystearate itself, not esterified as provided by this invention, requires the use of 10% by weight of the total in a grease prepared as described above, using the same mineral oil. Thus the ester of this invention has approximately half again as potent a thickening power as the unesterified soap, for the same weight of material; calculated on the molar content of oxystearate radicals, it is even more potent.

Using 10% of the product of Example V I in the same oil will produce a thicker grease, of a #3 grade, suitable for use in slowermioving systems than #2 grade.

While the invention has been described with reference to various particular preferred embodiments thereof, it is to be appreciated that modifications and variations can be made within the scope of the preceding specification and the following claims.

What is claimed is:

1. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of an ortho ester of a hydroxy-substituted fatty acid soap of the formula:

where R ,,R and R are each selected individually from the group consisting of hydrocarbon, halohydrocarbon, hydrocarbonoxyhydrocarbon and halo-hydrocarbonoxyhydrocarbon radicals of from 1 to 18 carbon atoms, and R and R are aliphatic hydrocarbon radicals containing together from 10 to 22 carbon atoms; M is an element selected from the group consisting of Al, Si and Ti and M is a metal of Groups I-III of the periodic table; Y is an anion; a a and a are integers each selected individually from 0 and 1, a +a +a =nm, n and m are integers, n is the valence of M, m has a value of from 1 to n, and x and y are integers the total of which equals the valence of M.

2. The grease of claim 1 wherein the said base fluid is a synthetic, hydrolyzable oleaginous base fluid.

3. The grease of claim 1 wherein the said ester is an ester of a hydroxystearic acid soap.

4. The grease of claim 1 wherein the said ester is an aluminate ester of a lithium soap of hydroxystearic acid.

5. The grease of claim 1 wherein the said ester is a silicate ester of a lithium soap of hydroxystearic acid.

6. The grease of claim 5 wherein the said ester is a silicate ester of an aluminum soap of hydroxystearic acid.

7. The method of lubricating which comprises interposing the grease of claim 1 between surfaces in frictional sliding contact.

8. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of an ortho ester of a hydroxy-substituted fatty acid soap of the formula:

where R and R are aliphatic hydrocarbon radicals containing together from to 22 carbon atoms, R" is selected from the group consisting of alkyl and alkoxyalkyl radicals of from 1 to 8 carbon atoms, Y is an anion, M is a metal of Groups I-II'I, M is an element selected from the group consisting of Al, Si and Ti, n and m are integers, n equals the valence of M, in has a value of from 1 to n, and x and y are integers which together equal the valence of 9. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of an alurninate ester of a Group I metal soap of hydroxy stearic acid.

10. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of an aluminate ester of an aluminum soap of hydroxy stearic acid.

:11. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of a silicate ester of a Group I soap of hydroxy stearic acid.

12. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of a titanate ester of a Group I metal soap of hydroxystearic acid.

13. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of a haloalkoxy silicate ester of a soap of hydroxystearic acid.

14. A lubricating grease consisting essentially of an oleaginous base fluid and a thickening amount of a fluoroalkoxy silicate ester of an aluminum soap of hydroxystearic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,799,656 Mikeska et al. July 16, 1957 2,899,389 Allison Aug. 11, 1959 2,922,762 Morway Jan. 26, 1960 2,932,659 Orthner et a1. Apr. 12, 1960 2,980,719 Haslam Apr. 18, 1961 

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF AN OLEAGINOUS BASE FLUID AND A THICKENING AMOUNT OF AN ORTHO ESTER OF A HYDROXY-SUBSTITUTED FATTY ACID SOAP OF THE FORMULA: 